BrowserTools

Random UUID Generator

Bulk UUID v4 identifiers, copy-ready

By Guga — BrowserTools maintainer, Tbilisi, Georgia Updated 2026-09-12
Free Private No uploads
What is Random UUID Generator?

Each identifier is a full 122 bits of entropy from the platform random source. Where crypto.randomUUID is available the page calls it directly; otherwise it fills sixteen bytes itself and then pins the version and variant nibbles — the high nibble of byte 6 forced to 4, the two high bits of byte 8 forced to 10 — which is what makes the third group always start with a 4 and the fourth always with one of 8, 9, a or b. The Format dropdown rewrites the finished string rather than the underlying bytes: Uppercase, No hyphens for systems that store a GUID as 32 characters, Braces for a .NET-style literal, and a urn:uuid: prefix for XML and RDF documents. Count accepts 1 to 1,000 and results stack one per line so they can be pasted straight into a migration file.

Generate one or thousands of RFC 4122 version 4 UUIDs instantly. Uppercase, braces and hyphen options included — ideal for database seeds, API mocks and test fixtures.

Private Random UUID Generator In Your Browser

Random UUID Generator is processed locally with client-side JavaScript. Your files never touch a server, and there is no queue to wait in.

Step-by-Step

How to use Random UUID Generator

1

Set How many? from 1 to 1000.

2

Pick a Format: Lowercase hyphenated, Uppercase, No hyphens, Braces or URN.

3

Press Generate UUIDs.

4

Copy the block; switching Format re-renders the same settings with the new shape, so no identifier is reused from a previous run.

Key Capabilities
  • Uses the platform's crypto.randomUUID where it exists and reproduces it byte-for-byte where it does not.
  • Version and variant nibbles are set explicitly, so the third group always begins with 4.
  • Five output shapes: lowercase, uppercase, hyphenless, braced and urn:uuid:.
  • Batch size from 1 to 1,000 identifiers per run.
Common Use Cases
  • A backend developer seeding a primary key column generates 500 version 4 identifiers and pastes them into a SQL fixture.
  • A front-end developer mocking a REST response needs 20 hyphenless values to match a C# API that serialises GUIDs as 32 characters.
  • A data engineer building RDF fixtures uses the URN format so each subject identifier parses as a real URI.
Clear Answers

Frequently Asked Questions

What makes a version 4 UUID different from a version 1?
Version 1 encodes a timestamp and a node address, so it leaks when and where it was created and sorts roughly by time. Version 4 is entirely random, which hides both at the cost of not sorting.
Can two runs produce the same value?
With 122 random bits per identifier, a collision across a few thousand identifiers is not a practical concern. It is still a probabilistic guarantee, not a uniqueness one — if your schema requires a hard uniqueness constraint, keep the database index.
Does the format change what is stored?
Only the presentation. The Braces and URN options are string rewrites of the same bytes, so pick the hyphenless or lowercase form when you are writing values that a downstream parser will re-parse rather than display.

Related Guides

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Random GeneratorsRandomness Explained: Crypto.getRandomValues vs Math.randomMath.random is fast but predictable. GetRandomValues is cryptographic. Understand entropy, seeding, modulo bias, and when each belongs in your code.